1. Field of the Invention
The present invention relates to a display apparatus with a display panel used for a computer apparatus, more particular to display apparatus working in conjunction with a computer apparatus and a storage medium.
2. Background Art
As a display apparatus for personal computers (PCs) and other monitors, liquid crystal displays have rapidly come into widespread use. These liquid crystal displays (LCDs) are configured to visualize an image formed on the liquid crystal surface of an LCD panel by uniformly illuminating the entire liquid crystal surface having a predetermined area with a back-light, which is a surface light source for illumination disposed behind the LCD panel.
The above-mentioned liquid crystal displays are used as a display for most notebook PCs. In notebook PC, both an alternating current (AC) power source and a direct current (DC) power source can be used. As is commonly known an AC adapter is connected to the PC to supply power from a commercial power source. To use DC power, a DC battery is attached to the PC to supply power from the battery. The technical challenge is to increase the amount of continuous operating time when using the DC power source.
To achieve this, efforts have been made to reduce power consumption in various components of a PC. In the LCD, the brightness of the LCD panel is automatically decreased when using a DC power source compared to when using an AC power source. To decrease the brightness of the LCD panel, the brightness of the back-light located behind the LCD panel is decreased. Decreasing the brightness of the LCD panel reduces power consumed by the back-light light source, thus contributing to the increase of the amount of continuous operating time by the DC battery. Still, there is a need for extending the continuous operating time when using the DC battery by further reducing power consumption.
In an intensive study to achieve the above-mentioned object, the inventors noted the refresh rate of LCD panels. To display a screen image on an LCD panel, the LCD panel is driven to redraw the screen a predetermined number of times per second. The driving frequency is called a “refresh rate (vertical operating frequency).”
Conventionally, the refresh rate has been fixed. The inventors on the other hand recognized that electric power required to drive the LCD panel could be reduced by decreasing the refresh rate.
The present invention overcomes this technical challenge and it is an object of the present invention to provide a display apparatus for a computer apparatus having a storage medium that allow power consumption to be reduced effectively.